The present invention relates to a hydraulically actuated wheel brake with a built-in pressure control device, in which a brake piston which acts on the brake elements has its outer circumference guided in a cylindrical bore formed in a housing, has two pressure surfaces each defining a different one of two working chambers and in which the pressure fluid inlet is connected directly to the first working chamber and via a valve to the second working chamber, the valve being actuatable upon attainment of a predetermined value of the inlet pressure.
In a known wheel brake of this type, for instance, FIG. 4 or German Patent DE-AS No. 1,430,226, the brake piston is of cup-like construction. The wall thickness of the cup forms the pressure surface defining the first working chamber, while the cup bottom forms the pressure surface defining the second working chamber. To seal the two working chambers, an insert is provided which is secured to the housing and on which the inner circumference of the brake piston is guided.
In this known wheel brake, three components, i.e. the cylindrical bore formed in the housing, the brake piston and the insert have to be assembled exactly concentrically relative to each other. This results in difficulties of manufacture and causes a considerable susceptibility to failure.
Although it has been desired for a long time to achieve a reduction of weight by fitting the pressure control device into the wheel brake and to simplify the assembly of the hydraulic unit, the known construction did not become popular on the market.